Iodine-125 radiolabeling of silver nanoparticles for in vivo SPECT imaging

Metal-based nanoparticle in cancer treatment: lessons learned and challenges

Cancer, being one of the deadliest diseases, poses significant challenges despite the existence of traditional treatment approaches. This has led to a growing demand for innovative pharmaceutical agents that specifically target cancer cells for effective treatment. In recent years, the use of metal nanoparticles (NPs) as a promising alternative to conventional therapies has gained prominence in cancer research. Metal NPs exhibit unique properties that hold tremendous potential for various applications in cancer treatment. Studies have demonstrated that certain metals possess inherent or acquired anticancer capabilities through their surfaces. These properties make metal NPs an attractive focus for therapeutic development. In this review, we will investigate the applicability of several distinct classes of metal NPs for tumor targeting in cancer treatment. These classes may include gold, silver, iron oxide, and other metals with unique properties that can be exploited for therapeutic purposes. Additionally, we will provide a comprehensive summary of the risk factors associated with the therapeutic application of metal NPs. Understanding and addressing these factors will be crucial for successful clinical translation and to mitigate any potential challenges or failures in the translation of metal NP-based therapies. By exploring the therapeutic potential of metal NPs and identifying the associated risk factors, this review aims to contribute to the advancement of cancer treatment strategies. The anticipated outcome of this review is to provide valuable insights and pave the way for the advancement of effective and targeted therapies utilizing metal NPs specifically for cancer patients.

Functional Diversity in Radiolabeled Nanoceramics and Related Biomaterials for the Multimodal Imaging of Tumors

Nanotechnology advances have the potential to assist toward the earlier detection of diseases, giving increased accuracy for diagnosis and helping to personalize treatments, especially in the case of noncommunicative diseases (NCDs) such as cancer. The main advantage of nanoparticles, the scaffolds underpinning nanomedicine, is their potential to present multifunctionality: synthetic nanoplatforms for nanomedicines can be tailored to support a range of biomedical imaging modalities of relevance for clinical practice, such as, for example, optical imaging, computed tomography (CT), magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT), and positron emission tomography (PET). A single nanoparticle has the potential to incorporate myriads of contrast agent units or imaging tracers, encapsulate, and/or be conjugated to different combinations of imaging tags, thus providing the means for multimodality diagnostic methods. These arrangements have been shown to provide significant improvements to the signal-to-noise ratios that may be obtained by molecular imaging techniques, for example, in PET diagnostic imaging with nanomaterials versus the cases when molecular species are involved as radiotracers. We surveyed some of the main discoveries in the simultaneous incorporation of nanoparticulate materials and imaging agents within highly kinetically stable radio-nanomaterials as potential tracers with (pre)clinical potential. Diversity in function and new developments toward synthesis, radiolabeling, and microscopy investigations are explored, and preclinical applications in molecular imaging are highlighted. The emphasis is on the biocompatible materials at the forefront of the main preclinical developments, e.g., nanoceramics and liposome-based constructs, which have driven the evolution of diagnostic radio-nanomedicines over the past decade.

The current status of stimuli-responsive nanotechnologies on orthopedic titanium implant surfaces

With the continuous innovation and breakthrough of nanomedical technology, stimuli-responsive nanotechnology has been gradually applied to the surface modification of titanium implants to achieve brilliant antibacterial activity and promoted osteogenesis. Regarding to the different physiological and pathological microenvironment around implants before and after surgery, these surface nanomodifications are designed to respond to different stimuli and environmental changes in a timely, efficient, and specific way/manner. Here, we focus on the materials related to stimuli-responsive nanotechnology on titanium implant surface modification, including metals and their compounds, polymer materials and other materials. In addition, the mechanism of different response types is introduced according to different activation stimuli, including magnetic, electrical, photic, radio frequency and ultrasonic stimuli, pH and enzymatic stimuli (the internal stimuli). Meanwhile, the associated functions, potential applications and developing prospect were discussion.

SPECT/CT Imaging of 111Ag for the Preclinical Evaluation of Silver-Based Antimicrobial Nanomedicines

With the growing interest in developing silver-based antimicrobials, there is a need to better understand the behavior of silver within biological systems. To address this, we showed that single-photon emission computed tomography (SPECT) is a suitable method to noninvasively image 111Ag-labeled compounds in mice. Formed by neutron irradiation of palladium foil, 111Ag can be rapidly isolated with a high degree of purity and stably incorporated into antimicrobial silver nanoparticles. The imaging showed that nanoparticles are retained in the lungs for up to 48 h following intratracheal instillation, with limited uptake into the systemic circulation or organs of the reticuloendothelial system. Furthermore, in a mouse model of pulmonary Pseudomonas aeruginosa infection, the nanoparticles reduced the bacterial burden by 11.6-fold without inducing the production of pro-inflammatory mediators. Overall, SPECT imaging with 111Ag is a useful tool for noninvasively visualizing the biodistribution of silver-containing compounds in rodents. This knowledge of how silver nanoparticles distribute in vivo can be used to predict their therapeutic efficacy.

Radioiodination of Modified Porous Silica Nanoparticles as a Potential Candidate of Iodine-131 Drugs Vehicle

There are challenges related to cancer treatment, namely, targeting and biocompatibility associated with a drug vehicle. This research aims to prepare a theranostic cancer vehicle based on porous silica nanoparticles (PSN) with controllable nanoparticle size, supporting targeting properties, and biocompatible. The synthesis method combined the Stöber process and liquid crystal templating using a dispersant and pore expander. Triethanolamine (TEA) and Pluronic F-127 were combined as a steric stabilizer and dispersing agent, while n-hexane was used as a pore expander. The amine functionalization was carried out using the 3-aminopropyl-triethoxysilane solution. Furthermore, radiolabeling of PSN using Iodine-131 and iodogen as oxidizing agents was carried out. The results showed that the best achievable PSN size was 100-150 nm with a polydispersity index of 0.24 using TEA-Pluronic F-127. The functionalization results did not significantly affect the radioiodination result. Radiochemical purity (RCP) values up to 95% were obtained in the radioiodination, while the labeled compounds were relatively stable with 12 mCi radioactivity, indicating the absence of radiolysis. The synthesized PSN was not toxic to normal cell samples up to a concentration of 150 μg/mL for PSN and 170 μg/mL for PSN-NH2. The cellular uptake testing results of the PSN-131I in cancer cell samples showed promising uptake ability.

Administration of Silver Nanoparticles in Diabetes Mellitus: A Systematic Review and Meta-analysis on Animal Studies

Biological features of silver nanoparticles in rising the insulin level of diabetic animal models were considered in recent years, which resulted in decreasing hyperglycemia condition. We reviewed the published literature to investigate the possible role of silver nanoparticles (Ag-NPs) throughout the treatment of diabetes mellitus in animal studies. In this systematic review and meta-analysis, we performed a search throughout the English literature of electronic databases, including Scopus, PubMed, and ISI Web of Science, up to the date of May 22, 2020. Primary outcomes and data regarding fast blood sugar (FBS), lipid profile, and liver enzyme were collected from the available articles, while the studies that did not provide sufficient information on the effects of silver nanoparticles through the course of diabetes mellitus were excluded. Our search yielded 1283 results that included five animal studies in the meta-analysis. The comparison between the plasma insulin level of the diabetic group treated by Ag-NPs with the diabetic control group displayed no significant differences with the P values = 0.299. In addition, significant differences were revealed by comparing the FBS level of the diabetic group treated by Ag-NPs with the diabetic control group (P value < 0.001). According to the present meta-analysis, the application of Ag-NPs in animal models resulted in displaying the anti-diabetic effects, which can be applied in future treatments. Furthermore, a correlation was noticed between these nanoparticles and the reduction of serum FBS among diabetic cases.

The Bio-Persistence of Reversible Inflammatory, Histological Changes and Metabolic Profile Alterations in Rat Livers after Silver/Gold Nanorod Administration

As a widely applied nanomaterial, silver nanomaterials (AgNMs) have increased public concern about their potential adverse biological effects. However, there are few related researches on the long-term toxicity, especially on the reversibility of AgNMs in vivo. In the current study, this issue was tackled by exploring liver damage after an intravenous injection of silver nanorods with golden cores (Au@AgNRs) and its potential recovery in a relatively long term (8 w). After the administration of Au@AgNRs into rats, Ag was found to be rapidly cleared from blood within 10 min and mainly accumulated in liver as well as spleen until 8 w. All detected parameters almost displayed a two-stage response to Au@AgNRs administration, including biological markers, histological changes and metabolic variations. For the short-term (2 w) responses, some toxicological parameters (hematological changes, cytokines, liver damages etc.) significantly changed compared to control and AuNRs group. However, after a 6-week recovery, all abovementioned changes mostly returned to the normal levels in the Au@AgNRs group. These indicated that after a lengthy period, acute bioeffects elicited by AgNMs could be followed by the adaptive recovery, which will provide a novel and valuable toxicity mechanism of AgNMs for potential biomedical applications of AgNMs.

Controlling optical trapping of metal-dielectric hybrid nanoparticles under ultrafast pulsed excitation: a theoretical investigation

Crucial to effective optical trapping is the ability to precisely control the nature of force/potential to be attractive or repulsive. The nature of particles being trapped is as important as the role of laser parameters in determining the stability of the optical trap. In this context, hybrid particles comprising of both dielectric and metallic materials offer a wide range of new possibilities due to their tunable optical properties. On the other hand, femtosecond pulsed excitation is shown to provide additional advantages in tuning of trap stiffness through harnessing optical and thermal nonlinearity. Here we demonstrate that (metal/dielectric hybrid) core/shell type and hollow-core type nanoparticles experience more force than conventional core-type nanoparticles under both continuous-wave and, in particular, ultrafast pulsed excitation. Thus, for the first time, we show how tuning both materials properties as well as the nature of excitation can impart unprecedented control over nanoscale optical trapping and manipulation leading to a wide range of applications.

The Influence of Size and Chemical Composition of Silver and Gold Nanoparticles on in vivo Toxicity with Potential Applications to Central Nervous System Diseases

The physicochemical and optical properties of silver nanoparticles (SNPs) and gold nanoparticles (GNPs) have allowed them to be employed for various biomedical applications, including delivery, therapy, imaging, and as theranostic agents. However, since they are foreign body systems, they are usually redistributed and accumulated in some vital organs, which can produce toxic effects; therefore, this a crucial issue that should be considered for potential clinical trials. This review aimed to summarize the reports from the past ten years that have used SNPs and GNPs for in vivo studies on the diagnosis and treatment of brain diseases and those related to the central nervous system, emphasizing their toxicity as a crucial topic address. The article focuses on the effect of the nanoparticle´s size and chemical composition as relevant parameters for in vivo toxicity. At the beginning of this review, the general toxicity and distribution studies are discussed separately for SNPs and GNPs. Subsequently, this manuscript analyzes the principal applications of both kinds of nanoparticles for glioma, neurodegenerative, and other brain diseases, and discusses the advances in clinical trials. Finally, we analyze research prospects towards clinical applications for both types of metallic nanoparticles.

Nanotechnology and its use in imaging and drug delivery (Review)

Nanotechnology is the exploitation of the unique properties of materials at the nanoscale. Nanotechnology has gained popularity in several industries, as it offers better built and smarter products. The application of nanotechnology in medicine and healthcare is referred to as nanomedicine, and it has been used to combat some of the most common diseases, including cardiovascular diseases and cancer. The present review provides an overview of the recent advances of nanotechnology in the aspects of imaging and drug delivery.

In vitro and in vivo sigma 1 receptor imaging studies in different disease states

The sigma receptor system has been classified into two distinct subtypes, sigma 1 (σ1R) and sigma 2 (σ2R). Sigma 1 receptors (σ1Rs) are involved in many neurodegenerative diseases and different central nervous system disorders such as Alzheimer's disease, Parkinson's disease, schizophrenia, and drug addiction, and pain. This makes them attractive targets for developing radioligands as tools to gain a better understanding of disease pathophysiology and clinical diagnosis. Over the years, several σ1R radioligands have been developed to image the changes in σ1R distribution and density providing insights into their role in disease development. Moreover, the involvement of both σ1Rs and σ2Rs with cancer make these ligands, especially those that are σ2R selective, great tools for imaging different types of tumors. This review will discuss the principles of molecular imaging using PET and SPECT, known σ1R radioligands and their applications for labelling σ1Rs under different disease conditions. Furthermore, this review will highlight σ1R radioligands that have demonstrated considerable potential as biomarkers, and an opportunity to fulfill the ultimate goal of better healthcare outcomes and improving human health.

All That Glitters Is Not Silver-A New Look at Microbiological and Medical Applications of Silver Nanoparticles

Silver and its nanoparticles (AgNPs) have different faces, providing different applications. In recent years, the number of positive nanosilver applications has increased substantially. It has been proven that AgNPs inhibit the growth and survival of bacteria, including human and animal pathogens, as well as fungi, protozoa and arthropods. Silver nanoparticles are known from their antiviral and anti-cancer properties; however, they are also very popular in medical and pharmaceutical nanoengineering as carriers for precise delivery of therapeutic compounds, in the diagnostics of different diseases and in optics and chemistry, where they act as sensors, conductors and substrates for various syntheses. The activity of AgNPs has not been fully discovered; therefore, we need interdisciplinary research to fulfil this knowledge. New forms of products with silver will certainly find application in the future treatment of many complicated and difficult to treat diseases. There is still a lack of appropriate and precise legal condition regarding the circulation of nanomaterials and the rules governing their safety use. The relatively low toxicity, relative biocompatibility and selectivity of nanoparticle interaction combined with the unusual biological properties allow their use in animal production as well as in bioengineering and medicine. Despite a quite big knowledge on this topic, there is still a need to organize the data on AgNPs in relation to specific microorganisms such as bacteria, viruses or fungi. We decided to put this knowledge together and try to show positive and negative effects on prokaryotic and eukaryotic cells.

Image-guided mathematical modeling for pharmacological evaluation of nanomaterials and monoclonal antibodies

While plasma concentration kinetics has traditionally been the predictor of drug pharmacological effects, it can occasionally fail to represent kinetics at the site of action, particularly for solid tumors. This is especially true in the case of delivery of therapeutic macromolecules (drug-loaded nanomaterials or monoclonal antibodies), which can experience challenges to effective delivery due to particle size-dependent diffusion barriers at the target site. As a result, disparity between therapeutic plasma kinetics and kinetics at the site of action may exist, highlighting the importance of target site concentration kinetics in determining the pharmacodynamic effects of macromolecular therapeutic agents. Assessment of concentration kinetics at the target site has been facilitated by non-invasive in vivo imaging modalities. This allows for visualization and quantification of the whole-body disposition behavior of therapeutics that is essential for a comprehensive understanding of their pharmacokinetics and pharmacodynamics. Quantitative non-invasive imaging can also help guide the development and parameterization of mathematical models for descriptive and predictive purposes. Here, we present a review of the application of state-of-the-art imaging modalities for quantitative pharmacological evaluation of therapeutic nanoparticles and monoclonal antibodies, with a focus on their integration with mathematical models, and identify challenges and opportunities. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > in vivo Nanodiagnostics and Imaging Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

131I-labeled polyethylenimine-entrapped gold nanoparticles for targeted tumor SPECT/CT imaging and radionuclide therapy

Purpose: Polyethylenimine (PEI) has been widely used as a versatile template to develop multifunctional nanosystems for disease diagnosis and treatment. In this study, we manufactured iodine-131 (131I)-labeled PEI-entrapped gold nanoparticles (Au PENPs) as a novel nanoprobe for single-photon emission computed tomography/computed tomography (SPECT/CT) imaging and radionuclide therapy. Materials and methods: PEI was PEGylated and sequentially conjugated with Buthus martensii Karsch chlorotoxin (BmK CT, a tumor-specific ligand which can selectively bind to MMP2), 3-(4'-hydroxyphenyl)propionic acid-OSu (HPAO), and fluorescein isothiocyanate to form the multifunctional PEI template for entrapment of Au NPs. Then, the PEI surface was radiolabeled with 131I via HPAO to produce the novel nanoprobe (BmK CT-Au PENPs-131I). Results: The synthesized multifunctional Au PENPs before and after 131I radiolabeling were well-characterized as follows: structure, X-ray attenuation coefficient, colloid stability, cytocompatibility, and radiochemical stability in vitro. Furthermore, BmK CT-Au PENPs-131I were suitable for targeted SPECT/CT imaging and radionuclide therapy of tumor cells in vitro and in a xenograft tumor model in vivo. Conclusion: The developed multifunctional Au PENPs are a promising theranostic platform for targeted imaging and treatment of different MMP2-overexpressing tumors.

Mathematical modeling in cancer nanomedicine: a review

Cancer continues to be among the leading healthcare problems worldwide, and efforts continue not just to find better drugs, but also better drug delivery methods. The need for delivering cytotoxic agents selectively to cancerous cells, for improved safety and efficacy, has triggered the application of nanotechnology in medicine. This effort has provided drug delivery systems that can potentially revolutionize cancer treatment. Nanocarriers, due to their capacity for targeted drug delivery, can shift the balance of cytotoxicity from healthy to cancerous cells. The field of cancer nanomedicine has made significant progress, but challenges remain that impede its clinical translation. Several biophysical barriers to the transport of nanocarriers to the tumor exist, and a much deeper understanding of nano-bio interactions is necessary to change the status quo. Mathematical modeling has been instrumental in improving our understanding of the physicochemical and physiological underpinnings of nanomaterial behavior in biological systems. Here, we present a comprehensive review of literature on mathematical modeling works that have been and are being employed towards a better understanding of nano-bio interactions for improved tumor delivery efficacy.

Applications of nanoparticles in biomedical imaging

An urgent need for early detection and diagnosis of diseases continuously pushes the advancements of imaging modalities and contrast agents. Current challenges remain for fast and detailed imaging of tissue microstructures and lesion characterization that could be achieved via development of nontoxic contrast agents with longer circulation time. Nanoparticle technology offers this possibility. Here, we review nanoparticle-based contrast agents employed in most common biomedical imaging modalities, including fluorescence imaging, MRI, CT, US, PET and SPECT, addressing their structure related features, advantages and limitations. Furthermore, their applications in each imaging modality are also reviewed using commonly studied examples. Future research will investigate multifunctional nanoplatforms to address safety, efficacy and theranostic capabilities. Nanoparticles as imaging contrast agents have promise to greatly benefit clinical practice.

Radiolabeled Molecular Imaging Probes for the In Vivo Evaluation of Cellulose Nanocrystals for Biomedical Applications

Cellulose nanocrystals (CNCs) have remarkable potential to improve the delivery of diagnostic and therapeutic agents to tumors; however, the in vivo studies on CNC biodistribution are still limited. We developed CNC-based imaging probes for the in vitro and in vivo evaluation using two labeling strategies: site-specific hydrazone linkage to the terminal aldehyde of the CNC and nonsite-specific activation using 1,1'-carbonyldiimidazole (CDI). The in vivo behavior of unmodified CNC, DOTA-CNC (ald.), and DOTA-CNC (OH) was investigated in healthy and 4T1 breast cancer mouse models. They displayed good biocompatibility in cell models. Moreover, the biodistribution profile and SPECT/CT imaging confirmed that the accumulation of ¹¹¹In-labeled DOTA-CNC (ald.) and ¹¹¹In-DOTA-CNC (OH) was primarily in hepatic, splenic, and pulmonary ducts in accordance with the clearance of nontargeted nanoparticles. The developed CNC imaging probes can be used to obtain information with noninvasive imaging on the behavior in vivo to guide structural optimization for targeted delivery.

Advantages and Limitations of Current Techniques for Analyzing the Biodistribution of Nanoparticles

Nanomedicines are typically submicrometer-sized carrier materials (nanoparticles) encapsulating therapeutic and/or imaging compounds that are used for the prevention, diagnosis and treatment of diseases. They are increasingly being used to overcome biological barriers in the body to improve the way we deliver compounds to specific tissues and organs. Nanomedicine technology aims to improve the balance between the efficacy and the toxicity of therapeutic compounds. Nanoparticles, one of the key technologies of nanomedicine, can exhibit a combination of physical, chemical and biological characteristics that determine their in vivo behavior. A key component in the translational assessment of nanomedicines is determining the biodistribution of the nanoparticles following in vivo administration in animals and humans. There are a range of techniques available for evaluating nanoparticle biodistribution, including histology, electron microscopy, liquid scintillation counting (LSC), indirectly measuring drug concentrations, in vivo optical imaging, computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine imaging. Each technique has its own advantages and limitations, as well as capabilities for assessing real-time, whole-organ and cellular accumulation. This review will address the principles and methodology of each technique and their advantages and limitations for evaluating in vivo biodistribution of nanoparticles.

Safety and efficacy of PLGA(Ag-Fe3O4)-coated dental implants in inhibiting bacteria adherence and osteogenic inducement under a magnetic field

Introduction

The placement of dental implants is performed in a contaminated surgical field in the oral cavity, which may lead to implant failure. Bacterial adhesion and proliferation (Streptococcus mutans, Porphyromonas gingivalis) often lead to implant infections. Although Ag nanoparticles hold great promise for a broad spectrum of antibacterial activities, their runoff from dental implants compromises their antibacterial efficacy and potentially impairs osteoblast proliferation. Thus, this aspect remains a primary challenge and should be controlled.

Materials and methods

In this study, PLGA(Ag-Fe₃O₄) was modified on the implanted tooth surface and was characterized by transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The magnetic and antibacterial properties were also determined.

Results

Results showed that Ag successfully bonded with Fe₃O₄, and Ag-Fe₃O₄ not only exerted superparamagnetism but also exhibited antibacterial activity almost identical to silver nanoparticles (nano-Ag). The PLGA(Ag-Fe₃O₄) coating could significantly maintain the antibacterial activity and avoid bacterial adhesion to the implant. Compared with the blank control group, PLGA(Ag-Fe₃O₄) under magnetic field-coated samples had a significantly lower amount of colonized S. mutans (P<0.01). Osteoblast proliferation results showed that the coated samples did not exhibit cytotoxicity and could promote osteoblast proliferation as shown by MTT, alkaline phosphatase, and the nucleolar organizer region count.

Conclusion

We developed a novel Ag biologically compatible nanoparticle in this study without compromising the nano-Ag antibacterial activity, which provided continuous antibacterial action.

Nanotechnology for Cancer Therapy Based on Chemotherapy

Chemotherapy has been widely applied in clinics. However, the therapeutic potential of chemotherapy against cancer is seriously dissatisfactory due to the nonspecific drug distribution, multidrug resistance (MDR) and the heterogeneity of cancer. Therefore, combinational therapy based on chemotherapy mediated by nanotechnology, has been the trend in clinical research at present, which can result in a remarkably increased therapeutic efficiency with few side effects to normal tissues. Moreover, to achieve the accurate pre-diagnosis and real-time monitoring for tumor, the research of nano-theranostics, which integrates diagnosis with treatment process, is a promising field in cancer treatment. In this review, the recent studies on combinational therapy based on chemotherapy will be systematically discussed. Furthermore, as a current trend in cancer treatment, advance in theranostic nanoparticles based on chemotherapy will be exemplified briefly. Finally, the present challenges and improvement tips will be presented in combination therapy and nano-theranostics.

Silver nanoparticles have lethal and sublethal adverse effects on development and longevity by inducing ROS-mediated stress responses

Silver nanoparticles (AgNPs) are widely used in the household, medical and industrial sectors due to their effective bactericidal activities and unique plasmonic properties. Despite the promising advantages, safety concerns have been raised over the usage of AgNPs because they pose potential hazards. However, the mechanistic basis behind AgNPs toxicity, particularly the sublethal effects at the organismal level, has remained unclear. In this study, we used a powerful in vivo platform Drosophila melanogaster to explore a wide spectrum of adverse effects exerted by dietary AgNPs at the organismal, cellular and molecular levels. Lethal doses of dietary AgNPs caused developmental delays and profound lethality in developing animals and young adults. In contrast, exposure to sublethal doses, while not deadly to developing animals, shortened the adult lifespan and compromised their tolerance to oxidative stress. Importantly, AgNPs mechanistically resulted in tissue-wide accumulation of reactive oxygen species (ROS) and activated the Nrf2-dependent antioxidant pathway, as demonstrated by an Nrf2 activity reporter in vivo. Finally, dietary AgNPs caused a variety of ROS-mediated stress responses, including apoptosis, DNA damage, and autophagy. Altogether, our study suggests that lethal and sublethal doses of AgNPs, have acute and chronic effects, respectively, on development and longevity by inducing ROS-mediated stress responses.

Chemisorption of iodine-125 to gold nanoparticles allows for real-time quantitation and potential use in nanomedicine

Gold nanoparticles have been available for many years as a research tool in the life sciences due to their electron density and optical properties. New applications are continually being developed, particularly in nanomedicine. One drawback is the need for an easy, real-time quantitation method for gold nanoparticles so that the effects observed in in vitro cell toxicity assays and cell uptake studies can be interpreted quantitatively in terms of nanoparticle loading. One potential method of quantifying gold nanoparticles in real time is by chemisorption of iodine-125, a gamma emitter, to the nanoparticles. This paper revisits the labelling of gold nanoparticles with iodine-125, first described 30 years ago and never fully exploited since. We explore the chemical properties and usefulness in quantifying bio-functionalised gold nanoparticle binding in a quick and simple manner. The gold particles were labelled specifically and quantitatively simply by mixing the two items. The nature of the labelling is chemisorption and is robust, remaining bound over several weeks in a variety of cell culture media. Chemisorption was confirmed as potassium iodide can remove the label whereas sodium chloride and many other buffers had no effect. Particles precoated in polymers or proteins can be labelled just as efficiently allowing for post-labelling experiments in situ rather than using radioactive gold atoms in the production process. We also demonstrate that interparticle exchange of I-125 between different size particles does not appear to take place confirming the affinity of the binding.

Deformable Discoidal Polymeric Nanoconstructs for the Precise Delivery of Therapeutic and Imaging Agents

Over the last 15 years, a plethora of materials and different formulations have been proposed for the realization of nanomedicines. Yet drug-loading efficiency, sequestration by phagocytic cells, and tumor accumulation are sub-optimal. This would imply that radically new design approaches are needed to propel the clinical integration of nanomedicines, overcoming well-accepted clichés. This work briefly reviews the use of deformable discoidal nanoconstructs as a novel delivery strategy for therapeutic and imaging agents. Inspired by blood cell behavior, these nanoconstructs are designed to efficiently navigate the circulatory system, minimize sequestration by phagocytic cells, and recognize the tortuous angiogenic microvasculature of neoplastic masses. This article discusses the notion of nanoparticle margination and vascular adhesion, as well as advantages associated with deformable particles. Finally, details on the synthesis, physico-chemical properties, and in vivo characterization of discoidal polymeric nanoconstructs are provided, with particular emphasis on their ability to independently control size, shape, surface properties, and mechanical stiffness. These nanoconstructs could help in gaining a deeper understanding of the mechanisms regulating the behavior of nanomedicines and identifying optimal delivery strategies for patient-specific therapeutic interventions.

Nanomaterials for In Vivo Imaging

In vivo imaging, which enables us to peer deeply within living subjects, is producing tremendous opportunities both for clinical diagnostics and as a research tool. Contrast material is often required to clearly visualize the functional architecture of physiological structures. Recent advances in nanomaterials are becoming pivotal to generate the high-resolution, high-contrast images needed for accurate, precision diagnostics. Nanomaterials are playing major roles in imaging by delivering large imaging payloads, yielding improved sensitivity, multiplexing capacity, and modularity of design. Indeed, for several imaging modalities, nanomaterials are now not simply ancillary contrast entities, but are instead the original and sole source of image signal that make possible the modality's existence. We address the physicochemical makeup/design of nanomaterials through the lens of the physical properties that produce contrast signal for the cognate imaging modality-we stratify nanomaterials on the basis of their (i) magnetic, (ii) optical, (iii) acoustic, and/or (iv) nuclear properties. We evaluate them for their ability to provide relevant information under preclinical and clinical circumstances, their in vivo safety profiles (which are being incorporated into their chemical design), their modularity in being fused to create multimodal nanomaterials (spanning multiple different physical imaging modalities and therapeutic/theranostic capabilities), their key properties, and critically their likelihood to be clinically translated.

Image-Guided Drug Delivery with Single-Photon Emission Computed Tomography: A Review of Literature

Tremendous resources are being invested all over the world for prevention, diagnosis, and treatment of various types of cancer. Successful cancer management depends on accurate diagnosis of the disease along with precise therapeutic protocol. The conventional systemic drug delivery approaches generally cannot completely remove the competent cancer cells without surpassing the toxicity limits to normal tissues. Therefore, development of efficient drug delivery systems holds prime importance in medicine and healthcare. Also, molecular imaging can play an increasingly important and revolutionizing role in disease management. Synergistic use of molecular imaging and targeted drug delivery approaches provides unique opportunities in a relatively new area called 'image-guided drug delivery' (IGDD). Single-photon emission computed tomography (SPECT) is the most widely used nuclear imaging modality in clinical context and is increasingly being used to guide targeted therapeutics. The innovations in material science have fueled the development of efficient drug carriers based on, polymers, liposomes, micelles, dendrimers, microparticles, nanoparticles, etc. Efficient utilization of these drug carriers along with SPECT imaging technology have the potential to transform patient care by personalizing therapy to the individual patient, lessening the invasiveness of conventional treatment procedures and rapidly monitoring the therapeutic efficacy. SPECT-IGDD is not only effective for the treatment of cancer but might also find utility in the management of several other diseases. Herein, we provide a concise overview of the latest advances in SPECT-IGDD procedures and discuss the challenges and opportunities for advancement of the field.

Biodistribution and fate of core-labeled 125I polymeric nanocarriers prepared by Flash NanoPrecipitation (FNP)

Non-invasive medical imaging techniques such as positron emission tomography (PET) imaging are powerful platforms to track the fate of radiolabeled materials for diagnostic or drug delivery applications. Polymer-based nanocarriers tagged with non-standard PET radionuclides with relatively long half-lives (e.g. 64Cu: t1/2 = 12.7 h, 76Br: t1/2 = 16.2h, 89Zr: t1/2 = 3.3 d, 124I: t1/2 = 4.2 d) may greatly expand applications of nanomedicines in molecular imaging and therapy. However, radiolabeling strategies that ensure stable in vivo association of the radiolabel with the nanocarrier remain a significant challenge. In this study, we covalently attach radioiodine to the core of pre-fabricated nanocarriers. First, we encapsulated polyvinyl phenol within a poly(ethylene glycol) coating using Flash NanoPrecipitation (FNP) to produce stable 75 nm and 120 nm nanocarriers. Following FNP, we radiolabeled the encapsulated polyvinyl phenol with 125I via electrophilic aromatic substitution in high radiochemical yields (> 90%). Biodistribution studies reveal low radioactivity in the thyroid, indicating minimal leaching of the radiolabel in vivo. Further, PEGylated [125I]PVPh nanocarriers exhibited relatively long circulation half-lives (t1/2 α = 2.9 h, t1/2 β = 34.9 h) and gradual reticuloendothelial clearance, with 31% of injected dose in blood retained at 24 h post-injection.

Silver nanoparticles induced oxidative and endoplasmic reticulum stresses in mouse tissues: implications for the development of acute toxicity after intravenous administration

Concerns have arisen about the health and environmental impacts of the increasing commercial use of silver nanoparticles (AgNPs). However, the toxic mechanisms and target tissues of AgNPs have not been fully defined. In this paper, we investigated the tissue toxicity of mice after intravenous administration of AgNPs at a single-dose of 0.2, 2 or 5 mg per kg (body weight), respectively. Biodistribution, endoplasmic reticulum stress, and oxidative stress were examined in mouse organs at eight hours after exposure. Stress markers, e.g. HSP70, BIP, p-IRE1, p-PERK, chop and xbp-1s proteins/genes, were significantly upregulated in a dose-dependent manner. In the liver, spleen, lung and kidney, high stress accompanied by apoptosis occurred. Low stress levels were observed in the heart and brain. Thus, it is proposed that the liver, spleen, lung and kidney are dominant target tissues of AgNP exposure. The lower stress and toxicity in the heart and brain were in agreement with lower AgNP accumulation. The present results demonstrated that AgNP exposure eventually resulted in permanent toxic damage by gradually imposing stress impacts on target organs. These findings highlight the potent applications of stress markers in future risk evaluation of silver nanoparticle toxicity.

Using Rose's metal alloy as a pinhole collimator material in preclinical small-animal imaging: a Monte Carlo evaluation

PURPOSE

Pinhole collimation is the most common method of high-resolution preclinical single photon emission computed tomography imaging. The collimators are usually constructed from dense materials with high atomic numbers, such as gold and platinum, which are expensive and not always flexible in the fabrication step. In this work, the authors have investigated the properties of a fusible alloy called Rose's metal and its potential in pinhole preclinical imaging. When compared to current standard pinhole materials such as gold and platinum, Rose's metal has a lower density and a relatively low effective atomic number. However, it is inexpensive, has a low melting point, and does not contract when solidifying. Once cast, the piece can be machined with high precision. The aim of this study was to evaluate the imaging properties for Rose's metal and compare them with those of standard materials.

METHODS

After validating their Monte Carlo code by comparing its results with published data and the results from analytical calculations, they investigated different pinhole geometries by varying the collimator material, acceptance angle, aperture diameter, and photon incident angle. The penetration-to-scatter and penetration-to-total component ratios, sensitivity, and the spatial resolution were determined for gold, tungsten, and Rose's metal for two radionuclides, (99)Tc(m) and (125)I.

RESULTS

The Rose's metal pinhole-imaging simulations show higher penetration/total and scatter/total ratios. For example, the penetration/total is 50% for gold and 75% for Rose's metal when simulating (99)Tc(m) with a 0.3 mm aperture diameter and a 60° acceptance angle. However, the degradation in spatial resolution remained below 10% relative to the spatial resolution for gold for acceptance angles below 40° and aperture diameters larger than 0.5 mm.

CONCLUSIONS

Extra penetration and scatter associated with Rose's metal contribute to degradation in the spatial resolution, but this degradation is not always substantial. The most important factor besides the collimator material was the acceptance angle. This should be kept to a minimum to prevent unnecessary scatter and penetration. For (125)I, the difference in spatial resolution between gold and Rose's metal is very small, 2.2% in the worst-case scenario. Based on these results, the authors conclude that Rose's metal is an alternative to standard materials not only for low-energy photon imaging but also for medium-energy applications that require low-cost, flexible pinhole configurations and designs, and that can tolerate a degraded spatial resolution.

Nuclear molecular imaging with nanoparticles: radiochemistry, applications and translation

Molecular imaging provides considerable insight into biological processes for greater understanding of health and disease. Numerous advances in medical physics, chemistry and biology have driven the growth of this field in the past two decades. With exquisite sensitivity, depth of detection and potential for theranostics, radioactive imaging approaches have played a major role in the emergence of molecular imaging. At the same time, developments in materials science, characterization and synthesis have led to explosive progress in the nanoparticle (NP) sciences. NPs are generally defined as particles with a diameter in the nanometre size range. Unique physical, chemical and biological properties arise at this scale, stimulating interest for applications as diverse as energy production and storage, chemical catalysis and electronics. In biomedicine, NPs have generated perhaps the greatest attention. These materials directly interface with life at the subcellular scale of nucleic acids, membranes and proteins. In this review, we will detail the advances made in combining radioactive imaging and NPs. First, we provide an overview of the NP platforms and their properties. This is followed by a look at methods for radiolabelling NPs with gamma-emitting radionuclides for use in single photon emission CT and planar scintigraphy. Next, utilization of positron-emitting radionuclides for positron emission tomography is considered. Finally, recent advances for multimodal nuclear imaging with NPs and efforts for clinical translation and ongoing trials are discussed.

Short-term changes in intracellular ROS localisation after the silver nanoparticles exposure depending on particle size

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Exposing cells to nanosilver particles (AgNPs) immediately induces ROS.

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Smaller AgNPs induce mitochondrial ROS production.

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AgNP-induced mitochondrial ROS are independent of particle internalisation.

Silver nanoparticles (AgNPs) induce the production of reactive oxygen species (ROS) and apoptosis. These effects are enhanced by smaller particles. Using live-cell imaging, we show that AgNPs induced ROS production rapidly in a size-dependent manner after exposure of cells to 70-nm and 1-nm AgNPs (AgNPs-70, AgNPs-1), but not AgNO₃. Exposure of cells to 5 μg/mL each of AgNPs-70, AgNPs-1 or AgNO₃ for 1 h decreased the cell viability by approximately 40%, 100% and 20%, respectively. ROS were rapidly induced after 5 and 60 min by AgNPs-1 and AgNPs-70, respectively, whereas AgNO₃ had no detectable effect. ROS production detected using the reporter dichlorodihydrofluorescein was observed in whole cells and mitochondria 5 and 60 min after exposure to AgNPs-1. The present study is the first, to our knowledge, to report the temporal expression and intracellular localisation of ROS induced by AgNPs.

Transfer of Silver Nanoparticles through the Placenta and Breast Milk during in vivo Experiments on Rats

Silver nanoparticles (NPs), widely used in the manufacture of various types of consumer products and for medical applications, belong to novel types of materials that pose potential risks to human health. The potential negative effects of the influence of these NPs on reproduction are insufficiently researched. A quantitative assessment of the transfer of metallic silver nanoparticles through the placenta and breast milk was carried out during an in vivo experiment. We used 34.9 ± 14.8 nm in size silver NPs that were stabilized by low-molecularweight polyvinylpyrrolidone and labeled with the (110m)Ag radioactive isotope using thermal neutron irradiation in a nuclear reactor. [(110m)Ag]-labeled NPs preparations were administered intragastrically via a gavage needle to pregnant (20(th) day of gestation) or lactating (14-16th day of lactation) female rats at a dose of 1.69-2.21 mg/kg of body weight upon conversion into silver. The accumulation of NPs in rat fetuses and infant rats consuming their mother's breast milk was evaluated using a low-background semiconductor gamma-ray spectrometer 24 and 48 hours following labeling, respectively. In all cases, we observed a penetration of the [(110m)Ag]-labeled NPs through the placenta and ther entry into the mother's milk in amounts exceeding by 100-1,000 times the sensitivity of the utilized analytical method. The average level of accumulation of NPs in fetuses was 0.085-0.147% of the administered dose, which was comparable to the accumulation of the label in the liver, blood, and muscle carcass of adult animals and exceeded the penetration of NPs across the hematoencephalic barrier into the brain of females by a factor of 10-100. In lactating females, the total accumulation of [(110m)Ag]-labeled NPs into the milk exceeded 1.94 ± 0.29% of the administered dose over a 48 h period of lactation; not less than 25% of this amount was absorbed into the gastrointestinal tract of infant rats. Thus, this was the first time experimental evidence of the transfer of NPs from mother to offspring through the placenta and breast milk was obtained.

Gold nanorods for target selective SPECT/CT imaging and photothermal therapy in vivo

The development of theranostic agents with high detection sensitivity and antitumor efficacy at low concentration is a challenging task for target selective imaging and therapy of cancers. In this study, folate-conjugated and radioactive-iodine-labeled gold nanorods (GNRs) were designed and synthesized for target selective SPECT/CT imaging and subsequent thermal ablation of folate-receptor-overexpressing cancers. Both (ortho-pyridyl) disulfide-poly(ethylene glycol)-folate and a short peptide, H(2)N-Tyr-Asn-Asn-Leu-Ala-Cys-OH, were conjugated on the surface of the GNRs through thiol chemistry. The tyrosine in the peptide sequence was introduced for radioactive-iodine labeling through an iodine-tyrosine interaction. The labeling efficiency of radioactive iodine was more than 99%. Radiochemical stability tests on iodine-125-labeled GNRs in human serum showed that 91% of the iodine-125 remained intact on the GNRs after incubation for 24 h. In vitro and in vivo results in this study confirmed the potential utility of folate-conjugated and iodine-125-labeled GNRs as smart theranostic agents. This type of platform may also be useful for the targeted SPECT/CT imaging and photothermal therapy of inflammatory diseases such as atherosclerosis and arthritis, in which folate-receptor-overexpressing macrophages play pivotal roles.

Nanoinformatics: a new area of research in nanomedicine

Over a decade ago, nanotechnologists began research on applications of nanomaterials for medicine. This research has revealed a wide range of different challenges, as well as many opportunities. Some of these challenges are strongly related to informatics issues, dealing, for instance, with the management and integration of heterogeneous information, defining nomenclatures, taxonomies and classifications for various types of nanomaterials, and research on new modeling and simulation techniques for nanoparticles. Nanoinformatics has recently emerged in the USA and Europe to address these issues. In this paper, we present a review of nanoinformatics, describing its origins, the problems it addresses, areas of interest, and examples of current research initiatives and informatics resources. We suggest that nanoinformatics could accelerate research and development in nanomedicine, as has occurred in the past in other fields. For instance, biomedical informatics served as a fundamental catalyst for the Human Genome Project, and other genomic and -omics projects, as well as the translational efforts that link resulting molecular-level research to clinical problems and findings.

Endothelial targeting of polymeric nanoparticles stably labeled with the PET imaging radioisotope iodine-124

Targeting of therapeutics or imaging agents to the endothelium has the potential to improve specificity and effectiveness of treatment for many diseases. One strategy to achieve this goal is the use of nanoparticles (NPs) targeted to the endothelium by ligands of protein determinants present on this tissue, including cell adhesion molecules, peptidases, and cell receptors. However, detachment of the radiolabel probes from NPs poses a significant problem. In this study, we devised polymeric NPs directly labeled with radioiodine isotopes including the positron emission tomography (PET) isotope (124)I, and characterized their targeting to specific endothelial determinants. This approach provided sizable, targetable probes for specific detection of endothelial surface determinants non-invasively in live animals. Direct conjugation of radiolabel to NPs allowed for stable longitudinal tracking of tissue distribution without label detachment even in an aggressive proteolytic environment. Further, this approach permits tracking of NP pharmacokinetics in real-time and non-invasive imaging of the lung in mice using micro-PET imaging. The use of this strategy will considerably improve investigation of NP interactions with target cells and PET imaging in small animals, which ultimately can aid in the optimization of targeted drug delivery.

Intrinsic therapeutic applications of noble metal nanoparticles: past, present and future

Biomedical nanotechnology is an evolving field having enormous potential to positively impact the health care system. Important biomedical applications of nanotechnology that may have potential clinical applications include targeted drug delivery, detection/diagnosis and imaging. Basic understanding of how nanomaterials, the building blocks of nanotechnology, interact with the cells and their biological consequences are beginning to evolve. Noble metal nanoparticles such as gold, silver and platinum are particularly interesting due to their size and shape dependent unique optoelectronic properties. These noble metal nanoparticles, particularly of gold, have elicited a lot of interest for important biomedical applications because of their ease of synthesis, characterization and surface functionalization. Furthermore, recent investigations are demonstrating another promising application of these nanomaterials as self-therapeutics. To realize the potential promise of these unique inorganic nanomaterials for future clinical translation, it is of utmost importance to understand a few critical parameters; (i) how these nanomaterials interact with the cells at the molecular level; (ii) how their biodistribution and pharmacokinetics influenced by their surface and routes of administration; (iii) mechanism of their detoxification and clearance and (iv) their therapeutic efficacy in appropriate disease model. Thus in this critical review, we will discuss the various clinical applications of gold, silver and platinum nanoparticles with relevance to above parameters. We will also mention various routes of synthesis of these noble metal nanoparticles. However, before we discuss present research, we will also look into the past. We need to understand the discoveries made before us in order to further our knowledge and technological development (318 references).

Toxicological studies on silver nanoparticles: challenges and opportunities in assessment, monitoring and imaging

Silver nanoparticles (Ag NPs) are becoming increasingly prevalent in consumer products as antibacterial agents. The increased use of Ag NP-enhanced products may lead to an increase in toxic levels of environmental silver, but regulatory control over the use or disposal of such products is lagging due to insufficient assessment on the toxicology of Ag NPs and their rate of release into the environment. In this article we discuss recent research on the transport, activity and fate of Ag NPs at the cellular and organismic level, in conjunction with traditional and recently established methods of nanoparticle characterization. We include several proposed mechanisms of cytotoxicity based on such studies, as well as new opportunities for investigating the uptake and fate of Ag NPs in living systems.